This invention relates generally to odor abatement in wastewater in anaerobic digestive lagoons. In one specific aspect, the invention relates to a method of treating wastewater lagoons using a fine spray of an aqueous solution of a chemical to react with the odor vapors emanating from the lagoon surface, converting the odors (e.g. H.sub.2 S and mercaptans) to non odor compounds.
Many industrial plants utilize lagoons (e.g. ponds) to stabilize and equalize wastewaters. By collecting and storing wastewaters in lagoons the biochemical oxygen demand (BOD) of the water is reduced. BOD is a means of estimating the degree of biodegradable contamination of wastewater. It is the amount (mg/liter) of oxygen required during stabilization of the decomposable organic matter by biochemical action. Storage of wastewater for relative long periods of time, typically 1 to 30 days, reduces the BOD and thus improves the quality of the effluent water. The stabilization can be accelerated by aeration in aerobic digestive systems.
The size of wastewater lagoons vary considerably, but generally cover from 1,000 square feet to several million square feet.
The most common source of odors in wastewater is reduced sulfur compounds such as H.sub.2 S and mercaptans which result from the anaerobic (bacteria) decomposition of biodegradable organic matter in the presence of sulfates. In aerobic digestive systems, odor generally is not a problem. The present invention is, accordingly, directed specifically to the treatment of anaerobic digestive systems.
The present methods of chemically treating wastewater for odor reduction include (a) aqueous treatment with an oxidant such as potassium permanganate; (b) chlorination of wastewater liquids with a chlorine compound such as elemental chlorine, sodium of calcium hypochlorite, or chlorine dioxide; and (c) ozoning. All of these systems are economically impractical for large lagoons.